The overall objective of this project is to determine the organization of the genes for mammalian low molecular weight RNA species (particularly U1 and U2 RNA), as well as their flanking sequences, and to characterize their transcripts. We wish to isolate clones containing gene and pseudogene sequences for U1 and U2 RNA from a human DNA library. The nucleotide sequences of these genes and their flanking regions will be determined. Another goal is to determine, by "Northern" hybridization blots, if transcripts much larger that 200 bases (and perhaps as long as 5 kilobases), containing U1 or U2 RNA sequences, can be detected, as suggested by our ultraviolet radiation transcription inactivation data (Nature 279, 80 (1979)).